A high-resolution unified observational data product of mesoscale convective systems and isolated deep convection in the United States for 2004–2017

Abstract

Abstract. Deep convection possesses markedly distinct properties at different spatiotemporal scales. We present an original high-resolution (4 km, hourly) unified data product of mesoscale convective systems (MCSs) and isolated deep convection (IDC) in the United States east of the Rocky Mountains and examine their climatological characteristics from 2004 to 2017. The data product is produced by applying an updated Flexible Object Tracker algorithm to hourly satellite brightness temperature, radar reflectivity, and precipitation datasets. Analysis of the data product shows that MCSs are much larger and longer-lasting than IDC, but IDC occurs about 100 times more frequently than MCSs, with a mean convective intensity comparable to that of MCSs. Hence both MCS and IDC are essential contributors to precipitation east of the Rocky Mountains, although their precipitation shows significantly different spatiotemporal characteristics. IDC precipitation concentrates in summer in the Southeast with a peak in the late afternoon, while MCS precipitation is significant in all seasons, especially for spring and summer in the Great Plains. The spatial distribution of MCS precipitation amounts varies by season, while diurnally, MCS precipitation generally peaks during nighttime except in the Southeast. Potential uncertainties and limitations of the data product are also discussed. The data product is useful for investigating the atmospheric environments and physical processes associated with different types of convective systems; quantifying the impacts of convection on hydrology, atmospheric chemistry, and severe weather events; and evaluating and improving the representation of convective processes in weather and climate models. The data product is available at https://doi.org/10.25584/1632005 (Li et al., 2020).

Summer Mean and Extreme Precipitation Over the Mid‐Atlantic Region: Climatological Characteristics and Contributions From Different Precipitation Types

“…They may be caused by the false classification of MCS/IDC precipitation as NC, a potential limitation of the MCS/IDC data set (Li et al., 2021). Warm cloud ( T b ≥ 241 K) and the temporal resolution of Gridrad reflectivity, which only considers reflectivity with ±3.8 min of each hour, lead to some convective systems being missed in the MCD/IDC data set (Li et al., 2021). Further improvement of the FLEXTRKR algorithm and higher‐resolution observations are necessary to solve these problems.…”

“…The MCS/IDC data set is a high‐resolution (4 km, hourly) observational data product containing the classification, tracking, and characteristics of MCS and IDC events in the U.S. east of the Rocky Mountains from 2004 to 2017 (Li et al., 2021). The data product is developed by using the Storm Labeling in Three Dimensions (SL3D) algorithm (Starzec et al., 2017) and an updated FLEXTRKR (Flexible Object Tracker) algorithm (Feng et al., 2019; Li et al., 2021) based on the National Centers for Environmental Prediction (NCEP)/the Climate Prediction Center (CPP) L3 4 km Global Merged IR V1 brightness temperature ( T b ) data set (Janowiak et al., 2017), the three‐dimensional (3‐D) Gridded NEXRAD Radar (Gridrad) data set (Homeyer & Bowman, 2017), and the NCEP Stage IV precipitation data set (Lin & Mitchell, 2005). In the data set, an MCS is defined as a cold cloud system (CCS) ( T b < 241 K) with CCS areas surpassing 60,000 km 2 for more than six continuous hours and containing at least six consecutive hours of Precipitation Feature (PF) with major axis length >100 km and embedded intense convective cell area ≥16 km 2 .…”

“…allowing us to investigate the contributions of different precipitation types to extreme daily precipitation. To analyze the sub‐daily extreme precipitation characteristics due to the <1‐day precipitation durations of most MCS/IDC events (Li et al., 2021), we also calculate the summertime top 1%/5% extreme hourly precipitation for each grid cell over the MAR by using a similar definition as that for extreme daily precipitation. Here, wet days/hours are days/hours with accumulated daily/hourly precipitation >0.01 mm (Layberry et al., 2006; X. Li et al., 2020; Piani et al., 2010).…”

“…The MCS/IDC data set is available at https://data.pnnl.gov/dataset/13218 (last access: June 18, 2020) (J. Li et al., 2020; Li et al., 2021). The authors download the IBTrACS version 4.0 data set from https://www.ncdc.noaa.gov/ibtracs/index.php%3Fname%3Dib%2Dv4%2Daccess (last access: May 7, 2020) (Knapp et al., 2018).…”

“…The MCS/IDC data set is available at https://data.pnnl.gov/dataset/13218 (last access: June 18, 2020) (J. Li et al, 2021). The authors download the IBTrACS version 4.0 data set from https://www.…”